maf/mas dilemma

[98gst62]

I have the GM Maft in blowthrough right now with the safc. the problem with it is I cant get a consistant tune with it even on the dyno, each pull is different. I am considering going to a drawthrough with the GM, but not sure if the inconsistancy will change. I want to tune it once and have it stay there until I do more mods. Or should I just rip it all out and go back to the stock 2g mas? I have all the parts to do either one. Any suggestions? thank you!

 

[98gst62]

anyone have experience with the GM Maft in drawthrough?

 

[timloomis]

If your dyno session's are on different days, the weather is probably doing it. The maft doesn't have a barometer or intake air temp sensor, so the tune changes day to day. That's one of the problems I'm having now, and why I just bought a safc.

 

[98gst62]

same day, the pulls were within minutes of each other

 

[dsm-onster]

If your dyno session's are on different days, the weather is probably doing it. The maft doesn't have a barometer or intake air temp sensor, so the tune changes day to day. That's one of the problems I'm having now, and why I just bought a safc.

What? It has an internal intake temp sensor and the Volume flow and the MAP (or BARO) is measured at the same time w/ the hot wire. If the maf was not accurate, then GM wouldn't use this or it's cousin variants on 99% of their v8s!

The ONE signal it spits out is an acurate MASS flow reading, not a volume flow reading that needs baro and air temp signals to complete the calculation for mass flow done by the ECU. That is why the temp signal and the baro signal from the MAF translator is clamped. The translator sends the ECU a signal that will give the ecu an accurate mass flow calc when using the clamped baro and temp values. . .

It has been my experience that the maf in draw through is VERY accurate. But The consistancy is the same for both orientations. Can you swap another same size GM MAF and see what happens? Are there any bends w/in 6 inches of the maf in blowthru? HAve you tried "clocking" the GM MAF?

What exactly do you mean by "inconsistant"?

 

[98gst62]

It has been my experience that the maf in draw through is VERY accurate. But The consistancy is the same for both orientations. Can you swap another same size GM MAF and see what happens? Are there any bends w/in 6 inches of the maf in blowthru? HAve you tried "clocking" the GM MAF?

What exactly do you mean by "inconsistant"?

The setup was installed correctly, no bends within 6in on either side, wires are all right. I had Torque Freaks do the dyno tune and they said it was just inconsistant, every pull was different. thats what i was told. i dont have another gm maf around but im sure this one is good, the car runs fine, i just want a good tune and be able to keep it until i do another mod. what is clocking??

 

[dsm-onster]

Inconsistant a/f ratio? Inconsistant lb/min? Inconsistant hp and torque?

Clocking is just rotating the MAF. Some guys have noted a difference when using reducer couplings 6" before instead of ON the MAF.

Is your PVC still connected? Are you getting any oil on the MAF? Have you triple checked for boostleaks? Where's your BOV/bypass valve located (I've had a leaky BOV w/in 6 inches play w/ my MAf readings)? Is your air straightener still in the GM MAF?

I know that the intake temp and baro output are clamped. Have you logged them? Are they consistant? What is their output?

Have you swapped in injectors and the MAFT at the same time? If so. I'd go back to the stock MAF and dial in the injectors w/ the safc. Then swap in a zeroed out MAFT and tweek the base settings of the maft to get the METERING close to the METERING of the OEM MAF(blowthru logs different than drawthru). Then fine tune w/ the SAFC to get the most horsepower. Have you just tried to use the MAFT to tune just to rule out the SAFC?